This invention relates generally to polyolefinic adjuvants and, more particularly, to polyolefinic compositions, solutions and emulsions for enhancing the efficacy of agricultural and horticultural biocides and nutrients or, alternatively, for direct use in the non-toxic extermination of insects.
The effectiveness of any topical agricultural or horticultural treatment depends primarily upon two factors: (1) The retention of the treatment on the plant surface for a time sufficient to achieve the desired result; and (2) coverage of the treatment to provide uniform benefit over the entire plant surface. In the parlance of the industry, a "sticker" is a material that increases the retention of sprays or dust deposits on plants by resisting various weather factors. A sticker is further defined as a substance which increases the firmness of attachment of finely-divided solids or other water-soluble or -insoluble materials to a solid surface, and which may be measured in terms of resistance to time, wind, water, mechanical or chemical action. Typically, stickers are substances such as latex or other adhesives that improve attachment of an active ingredient to sprayed surfaces. In the pesticidal context, stickers protect the active pesticide ingredient from wash-off due to rainfall, heavy dew or irrigation, and help prevent pesticide loss from wind or leaf abrasion.
Likewise, the industry defines a "spreader" as a substance which increases the area that a given volume of liquid will cover. Spreaders are also known as film extenders, wetting agents or surfactants. Notwithstanding the difference in terminology, all such substances reduce the surface tension of spray droplets, increase surface wetting and enhance coverage. Using terminology most often associated with surfactants, use of an anionic spreader on a plant increases the resistance of an active material to removal by rain, dew or irrigation. Anionics also prevent the active ingredient from being readily absorbed through plant cuticles, and such materials are, therefore, used when the effectiveness of the active material depends upon it remaining on the outer surface of the plant. Alternatively, non-ionic spreaders can be used to increase the transport of an active material through plant cuticles and are, therefore, recommended for use with systemic herbicides, nutrients and the like.
As mentioned above, a sticker/spreader combination is used frequently in conjunction or as an adjuvant with various active materials, including biocides, nutrients, plant growth regulators, repellents and the like, to spread the active material more evenly over a plant surface and, if not to promote absorption, to keep it there for a longer period of time. The search for an efficient, effective sticker/spreader meeting these basic requirements has been an on-going concern in the art. Various approaches and chemical systems have been used with certain success, but each has limited utility due to specific, well-defined problems, most of which are related to retention deficiencies and/or incompatibility with the active material or solutions thereof.
Polyvinylpyrrolidones have been used extensively, but are observed to behave more as an encapsulation agent than a sticker. These materials tend to dissolve only very slowly in water and the cost is prohibitive. The various polymenthenes and/or pinches provide reasonable sticking properties, but are difficult to emulsify. Such materials are relatively expensive and tend to be unstable over time, providing an inadequate shelf life under most storage conditions.
Polyethylenes are, perhaps, the most widely used sticker materials, but are--as with the polymenthenes--costly and difficult to emulsify. Performance is also problematic in that the films formed tend to wash off. Polymethylacrylates have also been used, but with limited success. These resins are highly insoluble and form a coating incompatible with many tank mixes. Various surfactants are also used, alone, and promoted as sticker/spreaders. However, as discussed above, without a sticker component, they do not afford to retain the treatment or active material on the plant surface for a sufficient time.
In summary, a considerable number of drawbacks and problems exist in the art relating to stickers and sticker/spreaders. There is a need for an improved sticker and/or sticker/spreader composition to more fully take advantage of the benefits available through use of various biocides, nutrients, repellents and the like.